1. Field of the Invention
The present invention relates to a lubricating device, a lubricant applicator, and a priming agent used therewith, and more particularly, to a lubrication system incorporated in electrophotographic image forming apparatuses, such as photocopiers, printers, facsimiles, or multifunctional machines having image forming capabilities, which includes a lubricant applicator to apply lubricant to a movable imaging surface, such as a photoconductive drum, a photoconductive belt, an intermediate transfer belt, or the like, and a priming agent used with the lubricant applicator.
2. Discussion of the Background
In electrophotographic image forming apparatuses, such as photocopiers, printers, facsimiles, or multifunctional machines, electrophotographic toner images are transferred from one surface to another, such as moving surfaces of a photoconductive drum or photoconductive belt, an intermediate transfer belt, or the like. Typically, such a transfer process is followed by cleaning of the imaging surface to remove residual toner and other matter including toner additives and paper dust in preparation for the next imaging cycle. One example of such cleaning process employs a cleaning blade to scrape off adhering materials with an edge held in frictional contact with a moving imaging surface.
Such a cleaning device occasionally fails to completely remove residual particles, where the operative edge of the cleaning blade is abraded or worn away due to continuous frictional contact with the imaging surface, making a gap that allows some material to bypass the cleaning process. Cleaning failure also occurs where toner particles used are small in size and/or round in shape, which tend to flow into narrow spaces between the cleaning blade and the imaging surface and eventually escape away from the cleaning device. In particular, a cleaning defect called “filming” occurs when toner residue including toner additives and paper dust passing through the cleaning gap builds up to form a layer adhering to the imaging surface.
To prevent such cleaning deficiencies, some electrophotographic imaging apparatuses lubricate an imaging surface used in contact with a cleaning blade. The lubrication process reduces frictional resistance between the imaging surface and the blade edge to prevent abrasion and wear of the both, while allowing residual materials to easily slip over the imaging surface. This enables the cleaning device to work properly and maintains a defect-free condition of the imaging surface over time.
For example, one conventional lubricating method uses a lubricant applicator or brush roller that supplies lubricant to an imaging surface cleaned by a cleaning blade. The brush roller is in sliding contact with the imaging surface and with a solid mass of lubricant pressed thereagainst by a spring, respectively. The lubricating device also includes a metering blade contacting the imaging surface downstream of the brush roller. In use, the brush roller rotates in a given direction to pick up lubricant in small portions from the solid mass and apply it to the imaging surface, followed by the metering blade spreading the applied lubricant into a thin layer of uniform thickness or depth over the imaging surface.
According to this method, the lubricating device is located separate and downstream from the cleaning blade, and lubricates the imaging surface subsequent to removal of residual toner by the cleaning process. The separate configuration enables the lubricant applicator to supply a constant amount of lubricant to the imaging surface irrespective of the amount of toner entering the cleaning process, which provides stable lubrication compared to a configuration where a lubricating device is provided as an internal and integral part of a cleaning device.
One problem with the lubricating method described above arises when a brand-new lubricating device is operated for the first time after installation. During initial operation, the lubricant applicator has little if any lubricant immediately after startup or until it begins to receive constant amounts of lubricant from the lubricant source. The result is insufficient lubricant supplied where the imaging surface contacts the metering blade.
Such insufficient lubrication often causes the edge or tip of the metering blade to fracture due to high friction on the imaging surface. Fractures in the blade edge, once created, make a gap between the metering blade and the imaging surface through which unregulated amounts of lubricant leak to contaminate areas downstream of the metering blade. These contaminants interfere with charging and thus impair uniformity of images produced therethrough.
Moreover, the blade edge can suffer fracture repeatedly whenever an existing device is worn out and requires installation of a new one. The risk of damaging the blade edge increases particularly when the metering blade has its operative edge pointing in a direction opposite to the direction of movement of the imaging surface for effectively spreading lubricant over the imaging surface.
To deal with initial lack of lubrication on an imaging surface, one conventional cleaning method proposes to coating a brand-new cleaning brush with a given amount of toner preparatory to installation in an imaging system. The preparatory coating of toner is designed to prevent a cleaning blade from bending back due to high friction on an imaging surface used in conjunction with the cleaning brush.
Unfortunately, application of such a conventional method does not provide a satisfactory solution to the problem with the lubricating device. Recent experiments have confirmed that the preparatory coating of toner on an imaging surface, a lubricant applicator, and/or a metering blade in brand-new, unused condition does not effectively reduce frictional resistance between the metering blade and the imaging surface in the lubricating device.
It has been also confirmed that the conventional method remains insufficient even when modified to use lubricant instead of toner as the preparatory coating. Although the preparatory coating of lubricant does reduce frictional resistance, the lubricating effect is temporary and dissipates in a short time after installation as the lubricant quickly passes through, eventually causing fracturing of the metering blade.
Hence, it is advantageous to have a lubrication system that can provide stable and constant lubrication on an imaging surface upon initial startup after installation.